Clock lubricant



FFlCEY 2,409,444 CLOCK LUBRICANT John D. Morgan,

South Orange, and Russell E.

Lowe, East Orange, N. I... assignom to Cities Service Oil Company, poration of Pennsylvani New York, N. Y., a cor- No Drawing. Application August 14, 1944.

Serial No. 549,494 r 2 Claims. (or 252-494;)

This invention relates to lubricants and more particularly to compositions for lubricating electric clocks, chronometers and similar precision timing devices.

The small synchronous electric motors, and associated gear trains, which constitute the timing units of most electric clocks and similar chrono phic devices. raise lubrication problems which not answered by any 01' the normal time piece oils, nor even by many of the special oils which are prepared for this specific work. As a uenerel rule the bearings and other moving parts of these motor units are lubricated but once, at the time oi manufacture, and the lubricant must lost for the full life of the device. It is accordinaly cmential ically stable to a high degree, resisting oxidatlon and polymerization, both of which chemical reactions tend to change the viscosity and lubricatine values. A further requirement is that the lubricant must have an extremely low volatility so that it will not evaporate during the life of the timing mechanism and leaving the bearings and other parts dry. Obviously in service of this hind it is very important that the lubricant shall not attack the bearings, pivots. and gears. and that it should tend to protect those parts from corrosion by the water vapor. and oxygen oi the atmosphere. In addition to all of the foregoing. is essential thatthe lubricant shall not react with or dissolve the painted and lacquered dials and other parts 01' a clock mechanism which ac-' tion would tend to destroy the utility of both the cficvice and the oil itself.

The principal object or the invention is to provide a lubricating oil which is chemicallv stable over estencied. periods of time. has a relatively low viscosity over a wide range of temperatures.

wustruction of electric clocks. and has no solidllt or chemical effect upon the paints and lacl uere normall used in such devices.

it is a further object of the invention to provide a time piece lubricant which is better adapted to meet lubrication requirements of synchro nous electric clocks than any of the lubricants now available for this purpose. and which may manufactured at a comparatively low cost from synthetically prepared lnrzredients that are rea iiy available in the domestic market.

We have discovered that very satisfactory lucants can be prepared from mixtures of triphosphate: di butyl phthalate; and triethyiene glycol di-2-ethyl butyrate. These increments are all that the lubricant shall be chem- .hich is non-corro ive to metals used in the country and are readily available on the open tively low cost.

of the liquid One specific example or a lubricant which is particularly well suited to the lubrication of electric clocks and similar devices has the following formula: v Percent by weight Tricresyl phosphate. 0 Di butyl phthalate 20 Tri ethylene glycol di-Z-ethyl butyrate-r 30 The resulting oil-like product has'a kinematic viscosity oi 13.49 centistokes at F., a value which is recognized as substantial at this high temperature and as being entirely adequate for the lubrication oi. electric'clock bearings. When the temperature of the liquid is dropped to --l0 F., its viscosity increases to a value of only 380.4 centistokes, which for this temperature is fairly low. Both the pour point and the cloud point are at some temperature below indicating that the composition does not begin to separate into its components nor to freeze at any temperature at which electric clocks can be expected-to operate. It will be evident from the foregoing that the viscosi ties of our fluid may remain relatively constant over a wide range of temperature. and that these properties are well within the viscosity-temperature specifications 60 1 thus 35 laid down by the leading manufacturers of elec- 49 fluid showed a loss 5 and long exposure at high temperature does not seem to produce any undesirable residues. A thin film oi the liquid was held at a temperature of F., for example, forsome 300 hours-after which it showed no tack development or other 5 indication of deterioration. At more moderate temperatures of the order of normal room. temperatures, there is no evidence of oxidation and gumming, even after very extended periods of exposure.

prepared synthetically in mm on A further feature of the advantage of this be said to be low, that they oi the composition is extremely- The solvent action of the lubricant upon lithc- Y graphic paints and lacquers was tested by immersing llthographed clock dials in the lubricant time and at temperatures for extended periods of well in exces 01' normal summer heat. At the conclusion or these tests the dials showed no ill eflects. The lubricant exhibited no tendency to remove the lithographic paint, or to soften it in the least.

The fluid has no corrosive action upon steel,

copper, and brass or other metals normally used in clock manufacture. In fact its presence on pivots, bearings, etc., serves to prevent rusting and atmospheric corrosion.

The foregoing composition is an ideal lubricant for lubricating electric clocks and the like, be-

- cause of its unique properties that particularly suit it for that type of service. We have found, however, that other desirable lubricants may be prepared from mixtures of these same ingredients within the following range: tricresyl phosphate 40 to 60 percent; di butyl phthalate to 15 percent; tri ethylene glycol dl-2- etc. -25 percent, the percentages being by weight. All of these compositions have good lubricating properties, are stable and resist gum-forming tendencies for long periods of time, and have little or no action uponlithographic paints. The percentages of the individual ingredients may be adjusted to bring out one or another of these properties forthe purpose of meeting the special requirements of individual problems.

Having described our invention what we claim is:

1. A lubricant consisting essentially of a mix ture of from to 60 percent of tricresyl phosphate, from 25 to 15 percent of di butyl phthalate, and from 35 to 25 percent of triethylene glycol di-2-ethylbutyrate, all of said percentages being by weight.

2. A lubricant for electric clocks and the like consisting of about percent by weight of tricresyl phosphate, about 20 percent by weight oi! di butyl phthalate, and about 30 percent by weight of triethylene glycol di-2-ethylbutyrate.

JOHN D. MORGAN. RUSSELL E. LOWE. 

